This invention relates to the preparation of alkoxylated tertiary amines from oxyalkylated alcohols. More particularly, this invention relates to a catalytic process for the substantially selective conversion of oxyalkylated alcohols to alkoxylated tertiary amines wherein the oxyalkylated alcohol is brought into contact with an amination catalyst of metallic iridium in the presence of hydrogen and a secondary amine at ambient pressure and at above ambient temperatures.
It is known in the art to manufacture alkoxylated tertiary amine compounds by reacting an oxyalkylated alcohol with a secondary amine in the presence of a reductive amination catalyst.
Kesling et al., European Patent Application No. 0 180 455 discloses a process for selectively preparing alkoxylated tertiary amine compounds having the general formula: ##STR1## by reacting an oxyalkylated alcohol of the formula: ##STR2## or a mixture of such alcohols, with a secondary amine of the formula HNR.sub.3 R.sub.4 at a temperature in the range of from about 150.degree. C. to 325.degree. C. and at elevated pressures of from about 50 psig to 3000 psig in the presence of from 0.5 to 20 wt. % of an amination catalyst based on the total reaction mixture and wherein R is a straight or branched chain alkyl group having from 1 to 11 carbon atoms, a cyclic alkyl group having from 5 to 10 carbon atoms, an aryl group having up to 12 carbon atoms, or an aralkyl or alkaryl group having up to 18 carbon atoms, R.sub.1 is a single unit or a series of units of the formula: ##STR3## wherein each unit R.sub.5 is independently selected from the group consisting of hydrogen and a straight or branched chain alkyl group having from 1 to 12 carbon atoms and x is an integer of from 0 to 40, R.sub.2 is hydrogen or a straight or branched chain alkyl group having from 1 to 12 carbon atoms, R.sub.3 and R.sub.4 are each independently selected from the group consisting of straight and branched chain alkyl groups having from 1 to 12 carbon atoms, cyclic alkyl groups having from 5 to 10 carbon atoms, 1 to 4 carbon atom alkyl substituted or unsubstituted benzyl groups and allyl.
Amination catalysts described as being useful in the process include Raney nickel, supported noble metals, and catalysts containing Cu, Cr and promoters such as nickel. Catalysts containing CuO and Cr.sub.2 O.sub.3 in various ratios, Cu-Cr supported on magnesium aluminate spinel and ruthenium on activated carbon are reported to be preferred catalysts. A selectivity to the alkoxylated tertiary amine product of 98% using, as an amination catalyst, 5 wt % copper chromite supported on magnesium aluminate spinel is disclosed in Example 31.
K. R. Smith in U.S. Pat. application Ser. No. 213,346 filed June 30, 1988 discloses a catalytic process for selectively preparing alkoxylated tertiary amines by reacting an oxyalkylated alcohol with a secondary amine in the presence of a combination of Raney nickel and molybdenum.
One problem that has been associated with the conversion of oxyalkylated alcohols to alkoxylated tertiary amines in addition to obtaining high yields of alkoxylated tertiary amines at comparatively high conversion levels based on the oxyalkylated alcohol starting material, is that the oxyalkylated alcohol reactants contain ether groups which are susceptible to rupture or cleavage during a conversion operation. This not only produces unwanted cleavage products but also results in decreased yields of the desired alkoxylated tertiary amine product containing the same ether linkage present in the starting oxyalkylated alcohol reactant.